Agreement is a legal relationship that is often done in the social life in the community.Agreement pursuant to Article 1313 of the Civil Code is an act in which one or more bind themselves to one or more other persons.Unwittingly, oral agreements are often done in people's lives. The purpose of this journal is to know how the legal power of oral agreement to claim someone do breach of contract.The intent of this legal power oral agreement in there is whether oral agreements have the legal power to be the primary consideration of the judge in deciding the case of breach of contract. This research is descriptive normative law. The data used is secondary data in the form of primary legal materials and secondary law. The data collection technique used is the study of documents and literature studies, research instrument is the Yogyakarta District Court Decision Number: 44/Pdt.G/2015/PN.Yyk. The analysis technique used is the deductive syllogism. That decision is about case breach of contract , which is between Subagyo as Plaintiff and Ary Kalista as Defendants. Ary Kalista has been sued by reason do breach of contract on oral agreements made by Subagyo and Ary Kalista. Ary Kalista pleaded by postulating that never made any oral agreement.But the judge ruled that Ary Kalista violates the agreement/breaches the contract. Oral agreements have the legal power to claim someone breach the contact, as long as the oral agreement proved to have been made by the parties, and has been in accordance with requirements validity of the agreement in Article 1320 of the Civil Code.